There's a handgun on the Soyuz attached to the Space Station. Does that count?
The Outer Space Treaty forbids placing weapons of mass destruction in space. Other than that handgun on the Soyuz, that's about it. That handgun is a weapon of bear or wolf destruction, not a weapon of mass destruction.
This question is a bit tougher to answer when you consider the fact that anything moving at 17,000 mph can be a rather potent kinetic weapon. China and the US each blew up one of their own satellites as a demonstration of their prowess. If they could destroy one of their own, they can certainly destroy satellites belong to some other country. The Outer Space Treaty doesn't appear to address anti-satellite weapons.